1. Field of the Invention
The present invention relates to an image-pickup apparatus on which an interchangeable lens can be mounted and an image-pickup system constituted thereby.
2. Description of the Related Art
In recent years, there is an increasing demand for the enhancement of performance of an image-pickup apparatus, such as a digital still camera and a digital video camera. In a lens interchangeable type image-pickup apparatus, a distance (back focus) from a lens closest to the image side to an image-pickup element, such as a CCD sensor, is different for each lens apparatus mounted on the image-pickup apparatus. For this reason, it is necessary to adjust the back focus for every different lens apparatus mounted on the image-pickup apparatus.
Thus, techniques for automatically adjusting the back focus are disclosed in Japanese Patent Laid-Open No. 2003-287664 and Japanese Patent Laid-Open No. 11-127376. In these techniques, data for adjusting the back focus is stored in the image-pickup apparatus. Therefore, if the back focus is once adjusted, the adjustment data is sent from the image-pickup apparatus to a lens apparatus when the lens apparatus is mounted, so as to enable the lens apparatus to correct the back focus on the basis of the adjustment data.
However, adjustment data corresponding to a lens apparatus which is mounted on the image-pickup apparatus for the first time, is not necessarily always stored in the image-pickup apparatus. Further, since the adjustment data are different for each combination of the lens apparatus and the image-pickup apparatus, it is preferred that the adjustment data are managed so as to be associated with identification data which enable the lens apparatuses and the image-pickup apparatuses to be identified, respectively.
In Japanese Patent Laid-Open No. 10-20181, there is disclosed an image-pickup apparatus into which the adjustment data and the identification data can be input by the user.
However, in the image-pickup apparatus disclosed in Japanese Patent Laid-Open No. 10-20181, it is difficult to perform accurate back focus adjustment. This is because in the image-pickup apparatus disclosed in Japanese Patent Laid-Open No. 10-20181, the same identification data is allocated for a plurality of lens apparatuses of the same type, and hence, the same back focus adjustment data is used for the plurality of lens apparatuses. Even for lens apparatuses of the same type, optimal back focus adjustment data for the respective lens apparatuses are different from each other due to the manufacturing error. Therefore, it is difficult to perform highly accurate back focus adjustment by using the same back focus adjustment data.
Further, in the image-pickup apparatus disclosed in Japanese Patent Laid-Open No. 10-20181, although the identification data and the adjustment data can be input by the user, the back focus adjustment performed by the user is inaccurate in many cases, and further, the usability of the image-pickup apparatus is deteriorated due to the time and labor for inputting these data in each adjustment.